Electrical projectile igniter



Sept. 30, 1930. H. RUHLEMANN `ELECTRICAL PROJECTILE IGNITER Filed Dec.16, 1929 BMM@ ffl Patented Sept. 30, 1930 UNITED STATES PATENT ol-FlcEHERBERT RHLEMANN, 0F SOMMERDA, GERMANY, lASSIIGNOR. T0 RHEINISCHEMETALLWAAREN- UND MASCHINENFABRIK, 0F DUSSELDORF-DERENDORF, GER- MANY, ACORPORATION 0F GERMANY Application led lDecember 16, 1929, Serial No.414,498, and in Germany June 14, 1929.

The electrical fuse of my U. S. Patent N o. 1,711,693, comprises twoopposed condensers with means for varying the potential of theirdischarges, the difference of potential gradually increasing until it issuflicient to ignite the ignition substance of the fuse. The object ofthe present invention is to provide a safety means for such fuses, thecondensers of which are charged from an outside .source either' 'ibefore or at the t1me of firing. Such means .through a high resistance,and, in some cases,

at the same time also, the balancing (ignition) circuit, leading throughthe ignltion medium from one condenser to the other, is

or are broken at a switch before the gun is fired, said switch, asshown, being in the form of an inertia or centrifugal switch, which isclosed only at or after the firing, i. e., is or are automaticallyclosed by the shock of firing or by the rotation of the projectile.Preferably, these switches are formed as double switches, so that, inone position, they connect, prior to firing, the outer charging contactsof the fuse leading to the source of energy, with the condenser ignitioncircuit poles, and at the same time disconnect the discharge circuit ofone of the condensers and the ignition circuit between the twocondensers, while after their automatic movement into the secondposition, at or after the firing, they disconnect the outer chargingcontacts from the condenser poles and, at the same time, close thedischarge circuit of one condenser and the balancing (ignition) cir'vcuit between the two condensers. -In this way, electric fuses 'withcondensers, as igni- ,tion current feeders and receiving their energyfrom an outside source, are afforded .a high degree of safety, in a verysimple manner,- against premature ignition, and also against anundesired accidental back discharge of the condenser potential through,the discharge circuit when it has not been previously short-circuited,which might occur, for example, during the flight of the projectile onaccount of atmospheric moisture or some other electric conductivesubstance bridging the charging poles.

The drawing is a diagrammatic representation of a projectile fuseconstructed in accordance with the invention,

The fuse, shown as a head fuse although it might as Well be a bottomfuse, contains, as usual, the two condensers c and d, like poles d and cof which are directly connected together throughthe igniter body, whiletheir other poles d2 and c2 are connected together bythe balancincircuit o through an electrical ignition suibstance'm and a spark gap p,acting as an automatic switch and preferably of the rare gas type. Thecondenser l can discharge itself, to automatically vary the potential ofits charge relatively to that of the condenser c, through the conductore and a high resistance g. The energy is supplied to the fuse by acharging device before the firing, or in sonic cases, at the timeoffiring in the barrel itself, from an outside source of current, notshown. The fuse is provided with contact rings k and k2, insulated fromeach other and from the body of-the fuse, and connected .for-charging,for example, with the positive pole of the battery. Ring 7: is connectedto the condenser coating d: and ring 7a2 to the condenser coating c?.The negative pole of the batter)V is then. in flunging, brought intocontact with the fuse body and through it with the coinilenser coatingsd and c.

In accordance with the present invention. a centrifugal switch 82,consisting, for example, of a spring Wire with a ball on its free end,is so mounted between the'onter charging contact ring k2, the condensercoating 02 and the circuit o, leading to the ignition medium fm, that,in the normal position of rest before firing, it interrupts the' circuito between the coatings d2 and c2 of the two condensers, but at the sametime closes the outer charging contact ring k2 to the coating c2.Furthermore, a second similar switch s maintains connection, before thefiring, between the outer charging 'contact ring c and the coating d2 ofthe condenser d while at the same time it interrupts the dischargecircuit e through the high resistance g. In transporting the igniter,therefore, its outer charging-contact rings lo and k2 are connected tothe condensers c and d, but the ignition circuit o and the dischargecircuit e. of the condenser d'are broken. .There is no possibility,therefore, of the formation of a -potential sufiicient for ignitionbetween the condenser coatings cl2 and 02 through the ignitionsubstance-m, during the charging of the condensers, nory of the buildingup of an ignition sufficient for ignition after disengagement of thecontacts of the battery from the charging contacts lc and 762, as longas the projectile is not rotated for any reason.

After the firing and at the commencement of rotation of the projectile,the centrifugal switches s and Vs2 swing outwardly, due to centrifugalforce, thereby automatically disconnecting the outer charging contactrings 7c and czof the fuse from the condensers c and d, and close thebalancing circuit o between the two condensers through the ignispondingto the potential, produced by the` charging of the condenser system, inthe equalizing circuit o between the condenser coatings cl2 and 02, Inthe event that, during the flight of the projectile before the saidnecessary; potential is reached, the charging Contact rings lc and k2should be conductively connected by any outside effects, for eX- ample,rain, then no equalization of they potential, already-built up between.the condensers d and c, around the ignition circuit o through thecharging circuits, can take place. f

The safety switches, according to the present invention, whichalternatively connect either the outer charging poles of the fuse or theignition circuit to the condensers, are advantageously used in allelectrical fuses containing condensers of any kind and connected up inany way.

I claim as my invention Y 1. Electrical fuse for projectiles,'lcomprising two condensers connected in opposition, one condenser being shortcircuited on itself, a high resistancein said short circuit, throughwhich said condenser may discharge to equalize its potential with thatof the other condenser, an inertia switch in said discharge shortcircuit, a second inertia switch in the circuit-connecting the twocondensers, and an ignition medium in said last-mentioned circuit, saidswitches acting automatically a'fter the'ring of the gun.

2. Electrical fuse for projectiles, comprising two condensers connectedin opposition, one condenser being short circuited on itself,

a high resistance in said short circuit, through tioned circuit, aninertia switch in said shortv circuit, and a second inertia switch insaid connecting circuit, whereby said switches in normal position closethe circuits from the charging contacts to the condensers and open saidshort circuit and said connecting circuit,

respectively, while in their second position after the projectile isfired, they open said charging circuits and close said short circuit andsaid connecting circuit.

. In an electrical fuse provided with two condensers and with chargingcontacts connected to said condensers, a short circuit, including a highresistance, around one of said condensers, a circuit connecting oppositepoles of said condensers, an ignition medium in said connecting circuit,an inertia switch in-the latter, and a similar switch in said chargingcircuits and in said short circuit, whereby the connections areautomatically charged for ignition when the projectile is firedu" 4. Anelectric fuse for projectiles and the like, comprising two condensers,charging circuits for the same, a discharge circuit from the condensers,an ignition medium in said discharge circuit, an inertia switch in saidcharging lcircuits and an inertia switch in said discharge and shortcircuits, whereby the charging circuits are automatically opened and thedischarge' and short circuits closed by the movement of the projectile.

` In testimony whereof, I affix my signature.

HERBERT nrnJEMA'NN.

